Inspection Procedure 2: Engine Overheating: Diagnosis

STEP 1. Remove the radiator cap and check for coolant contamination.
Q: Is the coolant contaminated with rust and oil?
1. YES: Replace it (Refer to ENGINE COOLANT CHANGE < 2.0L ENGINE NON-TURBO, 2.4L ENGINE > or Refer to ENGINE COOLANT CHANGE < 2.0L ENGINE TURBO > ).
2. NO: There is no action to be taken. Go to Step 2.
STEP 2. Check the radiator cap valve opening pressure.
NOTE: Be sure that the cap is clean before testing. Rust or other foreign material on the cap seal will cause an improper reading.
1. Use a cap adapter to attach the cap to the tester.
2. Increase the pressure until the gauge indicator stops moving.
  Minimum limit: 83 kPa (12 psi)
  
  Standard value: 93 - 123 kPa (14 - 18 psi)
Q: Does the reading remain at or above the minimum limit?
1. YES: Go to Step 3.
2. NO: Replace the radiator cap. Then go to Step 5.
  
  Fig 1: Checking Radiator Cap Valve Opening Pressure
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
STEP 3. Check thermostat operation.
Refer to THERMOSTAT CHECK .

Q: Does the thermostat operate correctly?
1. YES: Go to Step 4.
2. NO: Replace the thermostat, then go to Step 5.
STEP 4. Check the drive belt for slippage or damage.
- Refer to DRIVE BELT TENSION CHECK < 2.0L ENGINE Non-turbo >.
- Refer to DRIVE BELT TENSION CHECK < 2.0L ENGINE Turbo >.
- Refer to DRIVE BELT TENSION CHECK < 2.4L ENGINE >.
Q: Is the drive belt loose or damaged?
1. YES: Adjust or replace the drive belt, then go to Step 5.
2. NO: There is no action to be taken.
STEP 5. Retest the system.
Check the engine coolant temperature.

Q: Is the engine coolant temperature abnormally high?
1. YES: Return to Step 2.
2. NO: The procedure is complete.